Georg Ohm (1789–1854) was a German schoolteacher who, in his spare time and with home-made wires, uncovered the simplest and most useful rule in all of electricity. It cost him dearly at first — and made his name immortal in the end.
Ohm found that for many materials, the current through them is neatly proportional to the voltage
across them — the constant of proportionality being their
When Ohm published his great result, the reception was brutal — one official dismissed it as a "web of naked fancies," and he was so discouraged he resigned his teaching post. He spent years in near-poverty before the rest of Europe caught up and realised the schoolteacher had been right all along. Decades later the scientific world made it official by naming the unit of resistance after him — a quiet revenge that outlasts every critic.